The invention relates to the field of vehicle tire pressure monitoring, proximity object detection, and vehicle alarm system. Particularly, the invention relates to an apparatus for automatically monitoring tire pressure, detecting nearby objects and monitoring vehicle security, and methods for constructing and operating the apparatus.
Numerous innovations for each parts of the vehicle monitoring system have been provided in prior arts.
1. Tire Pressure Monitor
Pressure sensors have long been used to monitor tires for determining whether the tire was properly pressurized. Known methods for monitoring tire pressure included:
(a) A pressure sensor module installed inside the tire and transmitted the pressure data by wireless RF signal to a monitor located in the passenger compartment of a vehicle. With this method, system installation and battery replacement would be very inconvenient.
(b) A pressure sensing and transmission device mounted in the inner end of the tire valve, and transmitted the pressure data to a monitor. With this method, system installation and battery replacement would also be inconvenient.
(c) A pressure sensing and transmission device mounted on the tire valve stem. The device has a pressure sensitive diaphragm and spring switch for triggering the transmission of low-pressure warning signal to the monitor. With this method, however, the system can""t monitor the pressure data continuously.
U.S. Pat. No. 4,804,808 issued to Dal Cero on Feb. 14, 1989 discloses a pressure-sensing device that senses low tire pressure and signals low pressure using a transmitter and a receiver.
U.S. Pat. No. 4,694,273 issued to Franchino on Sep. 15, 1987 discloses a tire pressure-sensing device having a movable element to trigger a radio transmission signal, which is then received by a receiver for activating visual and acoustic alarms.
U.S. Pat. No. 5,289,161 issued to Huang on Feb. 22, 1994 discloses a pressure gauge having a diaphragm that pushes a spring-loaded rod between two switch devices which, when the tire is not properly pressurized, will trigger the sending of an encoded RF signal to a receiver for generating alarms.
U.S. Pat. No. 5,694,111 issued to Huang on Dec. 2, 1997 discloses an encoder unit and a transmitter circuit for a tire pressure sensor device for generating encoded RF signals received by a receiver with a display unit.
U.S. Pat. No. 4,734,674 issued to Thomas on Mar. 29, 1988 also discloses a tire pressure sensing device that, upon low pressure, transmits an encoded signal to a receiver having a plurality of display indicators on a front panel that are selectively activated to indicate the respective tire.
U.S. Pat. No. 4,319,220 issued to Pappas on Mar. 9, 1982 discloses a system for monitoring tire pressure of the tires having respective transmitters communicating alarm signals to a receiver.
U.S. Pat. No. 5,001,457 issued to Wang on Mar. 19, 1991 teaches a cab mounted monitor having a graphic display for visually indicating under-pressurized tire, which is identified by encoded signals transmitted from respective tire pressure sensing transmitters to the cab mounted central receiver.
Typically, these systems teach tire valve mounted pressure sensors responsive to individual tire pressures for generating encoded signals transmitted to a receiver with graphic displays. However, these teachings do not address or not able to resolve many practical issues, as described below:
(i) Continuous Pressure Monitoring
Properly pressurized tires are utmost important for safe driving and for prolonging the life of tires. Also, drivers often do not even aware that a tire is punctured and slowly leaking air, until the damaged tire went flat. A safe and practical system should monitor and display the tire pressure continuously for tire pressure maintenance and air leaking tire detection. The prior systems typically only generate alarms when the tire pressure is lower than a predetermined level and, therefore, provide very little information to the driver.
(ii) Sufficiently Small Pressure Sensor Size
A tire valve-stem mounted pressure sensor, which is usually in a cylindrical shape, must be small enough to be practical. Sensor size larger than 0.65 inch tall and 0.65 inch in diameter would present problems for sidewalk parking, car washing, and for secure mounting on the value stem. A larger sensor also would be more easily be detached from a valve stem of a fast moving vehicle due to tire rotation and airflow. It is technically very challenging to make a functional device that includes pressure sensor, motion detector, power supply, and RF signal transmission electronics in a very small package. Prior systems generally do not address methods to make small sensor modules.
(iii) Long Sensor Operating Life Between Battery Changes
A small sensor module can only have a mini-scale power supply. Therefore, a practical system must manage power consumption for providing a longer sensor operating life (preferably 18 months or more of normal usage) between battery changes. The few prior systems that discussed power saving at all did not present satisfactory methods.
(iv) Long and Large Vehicle Tire Pressure Monitoring
Prior arts generally do not address the problem of how to monitor tire pressures in larger vehicles with wheels far away from the receiver in the driver cab. A small sensor module physically can not be equipped with a very efficient antenna for RF message transmission, and the RF signal power is limited by the FCC regulations. Tire rotation would also create interference to further weaken the signal. Therefore, it is very difficult for a cab-mounted monitor to have a good reception for the weak data messages from the rear tire pressure sensors of a long truck or a trailer. Therefore, prior-art valve stem mounted sensors can not be successfully used on monitoring tire pressures in larger vehicles.
2. Object Detection Monitor
Safety concerns have led to numerous proposals for devices to be used in automobiles to detect the proximity of other vehicles or objects for collision avoidance. Known methods for object detection included:
(a) A radar-liked device that transmitted high frequency RF signals and then detected the object echo-reception signals; the signal travel time can be used to determine the object distance. However, with this method, the system is complicated, expensive, and has low range resolution for nearby objects.
(b) A device that transmitted infrared signals and then detected the intensity of the reflected signals to determine the object distance. However, with this method, the monitoring range is very short, and the system performance would be unstable due to environmental interference.
(c) A device that transmitted ultrasound signals and then detected the object echo-reception signals; the signal travel time can be used to determine the object distance.
U.S. Pat. No. 4,450,430 issued to Barishpolsky on Apr. 24, 1981 discloses a method for a diaphragm-type transducer assembly is mounted on the rear of an automobile to transmit ultrasound into left-and-right-hand target regions near the automobile. When the turn signal is turned on, it will transmit ultrasound pulse and listens for echo response from object.
U.S. Pat. No. 4,450,430 issued to Bonnefoy on Mar. 20, 1997 discloses a method for controlling a device for the ultrasound detection of objects in air, and to monitor object range during the vehicle reverse motion.
Typically, these systems teach ultrasonic object detection methods. However, these systems do not provide continuous visual range readings to the driver using wireless transmittal of detected object data, and the system installation would be difficult.
3. Vehicle Alarm System
Most automobile security systems relied on siren alarms for audio notification of vehicle security violation. If the vehicle owner was out of the hearing range, however, he or she will be unable to know whether the car alarm has been trigged. A known method of remote notification was to transmit a coded RF signal, upon alarm activation, to a portable receiver carried by the vehicle owner.
U.S. Pat. No. 5,905,432 issued to Greene on May 8, 1998 discloses a method for a vehicle anti-theft alarm system having a vehicle monitor with a battery, microprocessor, transmitter, audio generator and motion sensor, and the system also having a portable receiver.
U.S. Pat. No. 6,028,506 issued to Xiao on Feb. 22, 2000 discloses a method for a car alarm paging system, comprising an improvement of a conventional wireless phone pager and transmitter. The modified pager can be used both as a phone pager and also as a vehicle alarm transmitter for the notification of alarm activation to the pager carrier. A sample alarm trigger sensor module is provided in this invention.
Typically, these prior-arts teach vehicle alarm systems with a portable receiver, or a receiver with multiple uses. However, there are already many excellent vehicle, alarm systems available, and what these systems lacking is a method to remotely notify the user upon vehicle security violation. Therefore, a practical notification solution is not necessary to invent a more sophisticate alarm system with a remote receiver, but to invent a stand-alone notification system that can be coupled with a user-chosen alarm system.
Even though prior innovations may be suitable for the specific individual purpose to which they address, they differ from the present invention as hereinafter contrasted.
A main object of the present invention is to provide a wireless vehicular safety monitoring system, which can monitor tire pressure, detect objects behind the vehicle, and remotely notify vehicle security violations.
Another object of the invention is to provide a small battery-operated monitor unit, which can display individual tire pressure and detected-object range, and which can be carried by the vehicle owner for learning about car alarm activation from as far as 1000 feet away.
Another object of the invention is to provide a power-conservation method and apparatus, which allow the monitor unit to use minimal power when the vehicle is turned off. When a car is operating, its battery voltage is higher than when the engine is turned off. This system used a battery-voltage sensor module to detect the vehicle engine on/off status, and then transmit the status via RF signal to the monitor unit. Therefore, in engine-off time, the monitor unit can go to sleep and only wake up 10 milliseconds for every 2 seconds to detect any new engine-on message or alarm trigger message. This power-saving method enables the monitor unit to operate on a single 1.5V AA size battery for over six months.
Another object of the invention is to provide another power-conservation method and apparatus, which allow the tire pressure sensor module to stop consuming power when the vehicle is stationary. The tire pressure sensor module used omni-directional mercury roll motion switch for controlling its battery power supply, which will be turned on only while the vehicle is moving. This power-saving method enables the sensor module to operate on one set of button battery for over 18 months.
Another object of the invention is a method for constructing miniature sensor modules by first laying out print circuit and mounting components on a flexible rectangular sheet. Then the circuit sheet is vertically mounted on the base print circuit board for circularly surrounding the protruding pressure sensor, so that optimal utilization of space inside the module housing can be realized.
Another object of the invention is a method for mounting ultrasonic transducers on the license plate holder. And a method for transmitting range data of detected objects to the monitor unit by coded RF signal.
Another object of the invention is a method to re-transmit the sensor module RF signals for enhancing monitor signal reception. For example, signals from tire pressure sensor modules mounted on the rear tire stems of a long truck or trailer might be too weak for the cab-mounted monitor to receive. A RF signal repeater, installed near the rear section of the truck, can pick up the sensor module signal there and then re-transmit the signal to the monitor via a more efficient antenna.
The present invention is directed toward a vehicular monitoring system that gathers information through wireless sensor modules. Actual working models have been constructed to prove the practicality of the invention. The invention has provided numerous innovations to enable the making of a viable product.
The invention has the advantages of integrating several essential vehicle-monitoring functions into one package, and displaying the information on a battery-operated monitor unit, which can be put on any viewable location inside the vehicle, or be carried by the vehicle owner for remote notification. The monitor unit is designed to be small and durable, using one 1.5V AA battery that can support over six months of operation.
Another advantage of the invention is to provide a practical tire pressure monitoring solution. Prior proposals have discussed various concepts of monitoring tire pressure with a valve stem mounted sensor. Until now, however, very few (if any) such products are available on the market. This is a clear indication of its technical difficulties. The present invention overcomes the technical challenges by providing means to miniaturize the sensor module and to prolong its operational life between battery changes. The working tire pressure sensor module has a diameter and height of only 0.62 inches, and can last almost 18 months without needing to replace batteries.
Another advantage of the invention is to provide a practical tire pressure monitoring solution for all vehicles, large and small, by using RF signal repeaters to relay signals from farther away sensors to where the monitor is mounted.
Another advantage of the invention is to provide a practical solution for a driver to learn about the presence and distance of rear objects during vehicle reverse motion. The invention provided means for easy installation of ultrasonic transducers on the license plate holder, and for transmitting detected object range to the monitor unit via encoded RF signal.
Another advantage of the invention is to provide an effective way for vehicle owner to learn about vehicle alarm activation from as far as 1000 feet away.